[Chao Li <li.evan.chao@gmail.com>]

Hi,

I am testing graph tables today and noticed an improper error message when dropping a property.

Here is a simple repro:
```
evantest=# CREATE TABLE t1 (a int PRIMARY KEY, b int);
CREATE TABLE
evantest=#
evantest=# CREATE PROPERTY GRAPH g
evantest-#     VERTEX TABLES (
evantest(#         t1
evantest(#             LABEL l1 PROPERTIES (a AS p1)
evantest(#             LABEL l2 PROPERTIES (b AS p2)
evantest(#     );
CREATE PROPERTY GRAPH
evantest=#
evantest=# ALTER PROPERTY GRAPH g
evantest-#     ALTER VERTEX TABLE t1
evantest-#     ALTER LABEL l1 DROP PROPERTIES (p2);
ERROR:  could not find tuple for label property 0
```

This does not look like a normal user-facing SQL error message.

Looking into the code, AlterPropGraph() checks whether the property exists in the graph, but does not check if label property exists. As a result, InvalidOid can be passed to ObjectAddressSet() and then to performDeletion().

The fix is simple, just check the label-property OID before trying to delete it. I also added a regress test.

With the patch, the error becomes:
```
evantest=# ALTER PROPERTY GRAPH g
evantest-#     ALTER VERTEX TABLE t1
evantest-#     ALTER LABEL l1 DROP PROPERTIES (p2);
ERROR:  property graph "g" element "t1" label "l1" has no property "p2"
```

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

Attachments:

v1-0001-Fix-DROP-PROPERTIES-check-for-property-graph-labe.patch (application/octet-stream, 3.9K) download
From e9b4fb61856887f8bb3b34e60315382c0282b02f Mon Sep 17 00:00:00 2001
From: "Chao Li (Evan)" <lic@highgo.com>
Date: Fri, 24 Apr 2026 15:12:17 +0800
Subject: [PATCH v1] Fix DROP PROPERTIES check for property graph labels

When ALTER PROPERTY GRAPH ... DROP PROPERTIES drops a property from a
label, the code checked only whether the property existed in the graph's
property catalog. It did not verify that the property was actually
associated with the target label.

As a result, if the property was not present on the label,
GetSysCacheOid2(PROPGRAPHLABELPROP, ...) could return InvalidOid, which
was then passed to performDeletion().

Check the label-property mapping explicitly and report an undefined
property error when it is missing. Add a regression test for dropping a
nonexistent property from a label.

Author: Chao Li <lic@highgo.com>
Reviewed-by:
Discussion: https://postgr.es/m/
---
 src/backend/commands/propgraphcmds.c                | 13 +++++++++----
 src/test/regress/expected/create_property_graph.out |  2 ++
 src/test/regress/sql/create_property_graph.sql      |  1 +
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/backend/commands/propgraphcmds.c b/src/backend/commands/propgraphcmds.c
index 6d509fccf46..9a76332f2a8 100644
--- a/src/backend/commands/propgraphcmds.c
+++ b/src/backend/commands/propgraphcmds.c
@@ -1615,21 +1615,26 @@ AlterPropGraph(ParseState *pstate, const AlterPropGraphStmt *stmt)
 		{
 			char	   *propname = strVal(lfirst(lc));
 			Oid			propoid;
-			Oid			plpoid;
+			Oid			plpoid = InvalidOid;
 
 			propoid = GetSysCacheOid2(PROPGRAPHPROPNAME,
 									  Anum_pg_propgraph_property_oid,
 									  ObjectIdGetDatum(pgrelid),
 									  CStringGetDatum(propname));
-			if (!propoid)
+
+			if (OidIsValid(propoid))
+				plpoid = GetSysCacheOid2(PROPGRAPHLABELPROP,
+										 Anum_pg_propgraph_label_property_oid,
+										 ObjectIdGetDatum(ellabeloid),
+										 ObjectIdGetDatum(propoid));
+
+			if (!OidIsValid(plpoid))
 				ereport(ERROR,
 						errcode(ERRCODE_UNDEFINED_OBJECT),
 						errmsg("property graph \"%s\" element \"%s\" label \"%s\" has no property \"%s\"",
 							   get_rel_name(pgrelid), stmt->element_alias, stmt->alter_label, propname),
 						parser_errposition(pstate, -1));
 
-			plpoid = GetSysCacheOid2(PROPGRAPHLABELPROP, Anum_pg_propgraph_label_property_oid, ObjectIdGetDatum(ellabeloid), ObjectIdGetDatum(propoid));
-
 			ObjectAddressSet(obj, PropgraphLabelPropertyRelationId, plpoid);
 			performDeletion(&obj, stmt->drop_behavior, 0);
 		}
diff --git a/src/test/regress/expected/create_property_graph.out b/src/test/regress/expected/create_property_graph.out
index bc9a596ec89..d8c1c061c62 100644
--- a/src/test/regress/expected/create_property_graph.out
+++ b/src/test/regress/expected/create_property_graph.out
@@ -82,6 +82,8 @@ CREATE PROPERTY GRAPH g4
     );
 ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 ADD PROPERTIES (k * 2 AS kk);
 ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 DROP PROPERTIES (k);
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 DROP PROPERTIES (yy);  -- error
+ERROR:  property graph "g4" element "t2" label "t2" has no property "yy"
 CREATE TABLE t11 (a int PRIMARY KEY);
 CREATE TABLE t12 (b int PRIMARY KEY);
 CREATE TABLE t13 (
diff --git a/src/test/regress/sql/create_property_graph.sql b/src/test/regress/sql/create_property_graph.sql
index 241f93df302..8157f2b3c0a 100644
--- a/src/test/regress/sql/create_property_graph.sql
+++ b/src/test/regress/sql/create_property_graph.sql
@@ -75,6 +75,7 @@ CREATE PROPERTY GRAPH g4
 
 ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 ADD PROPERTIES (k * 2 AS kk);
 ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 DROP PROPERTIES (k);
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 DROP PROPERTIES (yy);  -- error
 
 CREATE TABLE t11 (a int PRIMARY KEY);
 CREATE TABLE t12 (b int PRIMARY KEY);
-- 
2.50.1 (Apple Git-155)

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